Drug addiction and associated HIV risk behavior are significant public health problems, and most addiction treatments fail to produce lasting behavior change. Prospective memory (ability to implement an intention in the future; e.g., remember to take medication, attend a scheduled meeting) may play a critical role in behavior change such as in addiction treatment (i.e., in order to behave differently, one has to remember to behavior differently). Despite an intuitive role for prospective memory in addiction and findings of impaired prospective memory in drug abusers, no study has targeted prospective memory for treatment. Prospective memory also provides a mechanistic account of exciting but theoretically challenging findings that working memory training decreased delay discounting (people showed greater self-control by choosing larger later rewards over smaller sooner rewards in a lab task) in addicted individuals, and reduced drinking in alcoholics. Prospective memory (which relies on working memory) is the missing link because a larger working memory capacity is more likely to have space to hold long term goals in mind (prospective memory) while faced with other demands including temptations at conflict with those longer term goals. Improved prospective memory results in a person more successfully obtaining longer term rewards, which over time reinforces greater valuation of delayed rewards. Working memory training only addresses 1 of multiple components of prospective memory. Thus, this highly innovative proposal will develop the 1st prospective memory training to encompass the multiple components of prospective memory (working memory, retrospective memory, executive functions), in order to increase self- control (ability to wait for delayed rewards), and therefore reduce drug use and associated HIV risk behavior. The computerized prospective memory training will use immersive technology to simulate everyday life prospective memory challenges. 3 studies in methadone patients who use cocaine will move from basic research to refinement of clinical intervention. Exp. 1 will inform intervention development by determining the optimal # of prospective memory tasks (intentions to remember) for subsequent experiments (Aim 1a). Exp. 2 is a 'proof of concept' test of the hypothesis that prospective memory training improves prospective memory (Aim 2a), and will provide 'dose-response' information to determine the optimal # of training sessions (Aim 2b). Exp. 3 is a randomized controlled trial (3 groups: prospective memory training, working memory training, control) to test the preliminary efficacy of the prospective memory training to improve the target behaviors. We hypothesize that prospective memory training will decrease delay discounting (Aim 3a; primary), drug use, and HIV risk behavior (Aim 3b; secondary), relative to control. A secondary hypothesis is that prospective memory training will produce greater decreases in delay discounting than working memory training. In addition to drug dependence and HIV, data from this project have broad implications for prevention and treatment of the many clinical disorders in which behavior change is critical (obesity, cardiovascular disease, cancer, diabetes).